150 091 Lecture 5 - Commentary on Lecture 5 Jan. 27, 2009...

Commentary on Lecture 5 Jan. 27, 2009 Contrary to the current fad diets, your body thinks carbohydrates (glucose) as an important component of your daily diet. Why else would it make such an effort to maintain a relatively constant blood glucose level? Glucose as I’ve said previously is the preferred energy source. About 25% of your carbohydrate intake is used as glucose in your brain. After a normal (carbohydrate containing) meal your body begins to convert the carbohydrate, protein and fat molecules into their components. As soon as a monomer is released it can gain entry into any cell it comes into contact with. It can happen in your mouth although not much is absorbed there because food is not in your mouth very long. After a period of time (a couple of hours) in your stomach where foods are being partially digested , broken into smaller pieces, the stomach contents are released bit by bit into the small intestine where the final conversion to monomers occurs and they can be absorbed as the foot molecules move down the length of the small intestine. The normal blood glucose concentration is kept close to 1 gram/liter of blood (in chemical terms it’s 5 millimolar). Since 1 gram is about 1/30 th of an ounce, you can see it’s not a very high concentration. The total amount of glucose in the blood of an adult is about 5 grams…1/6 th of an ounce. Although that would seem a very small amount even 1 gram of glucose contains enough glucose molecules to supply each of your 200 trillion cells with about 10 million glucose molecules. When you calculate how much carbohydrate is in the recommended (not fad) 2,000 calorie daily diet, the 1100 calories of carbohydrates (55% of 2,000) is equal to 275 grams of glucose (I’ll let you figure this one out ). After a meal the blood glucose concentration begins to rise as glucose enters the bloodstream. When it reaches about 1.6 g/L (grams/Liter) your pancreas secretes insulin, a protein hormone that travels through the bloodstream and attaches by way a special

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